Liver resections are used frequently for both primary and secondary hepatic tumors and offer approximately 20% to 50% 5-year survival depending on the type of malignancy. In hepatic surgery, both blood loss and transection time are the main determinants of operative outcome. Intraoperative blood loss during liver transection has been specifically associated with preoperative complications and, in turn, perioperative blood transfusion has been reported to increase recurrence rate and decrease survival after resection of the malignancies of the liver. Therefore, in addition to the conventional clamp crushing or finger fracture techniques, other techniques such as ultrasonic dissector, water jet dissector or argon beam coagulator have been intensively employed in order to reduce intraoperative blood loss.
Electrosurgical devices generally fall into two categories, monopolar and bipolar. In a monopolar device, a radio frequency signal is supplied to an active electrode which is used to treat tissue at a target site, an electrical circuit being completed by a grounding pad which is generally a large area pad attached to the patient at a location remote from the target site. In contrast, in a bipolar arrangement, both an active and a return electrode are present on the instrument, and the current flows from the active electrode to the return electrode.
Typically, electrosurgical devices are handheld and insulated (except at the working tip) where high frequency electrical energy is delivered through a conductive element to the surgical site. If cutting of tissue is desired, a tip with a sharp or electrically focusing edge is needed. If coagulation of tissue is desired, then a blunt or electrically spreading electrode is needed. In addition, the tissue to be cauterized is often obscured by a pool of blood or smoke.
Efficient and safe liver parenchymal transection is dependent on the ability to address parenchymal division and hemostasis simultaneously. Because no single instrument adequately addresses both tasks at the same time, most hepatic parenchymal transections are performed using a combination of instruments and techniques.
One of the most recent and most efficient methods of liver transection (in terms of reduced blood loss and short transection time) involves saline-linked radio frequency technology, used either alone or in combination with other methods of division or dissection of the liver (cf. EP 1435867-A and Y. Sakamoto et al., “Bloodless liver resection using monopolar Floating Ball plus liga Sure diatehrmy: preliminary results of 16 liver resections”, Worl J Surg 2004, vol. 28, pp. 166-172). This technology transfers radio frequency energy to the liver through saline dripping at the tip of the device. Positive features of this technology are a reduced blood loss during transection (it can be reduced to less than 200 ml of blood for a wedge resection or a segmentectomy), and a fast transection time. However, this technology still presents several drawbacks, such as the following: (1) As the technology is dependent on the rate of saline solution release, an insufficient release can cause scalding of the liver parenchyma which would make it difficult to identify blood vessels or the main hepatic ducts and, therefore, increase the chance of hilar injury during liver transection; on the other hand, an excessively saline solution release can cause an insufficient coagulation. (2) In order to achieve appropriate pre-coagulation, the devices based on this technology (even the latest models) are not sharp enough, a feature that impair and delay final cutting of the liver. (3) A depth of 3 to 5 mm of necrotic tissue is produced along the transection plane, which in cirrhotic patients with limited remnant reserve may give rise to an uncertain resection.
The approach based on the concept of pre-coagulating tissue prior to transection of the liver in order to obtain better hemostasis has been used by Weber et al. (cf. “New technique for liver resection using heat coagulative necrosis”, Ann Surg 2002, vol. 236, pp. 560-563), who pioneered the use of radio frequency needle electrodes to obtain a 1 or 2-cm wide line of coagulation at the resection line before dividing the line with a scalpel, thereby permitting bloodless liver resection. However, this technique shows some limitations, namely, it is time-consuming, and the surgeon just coagulate the tissue with a first instrument, a second instrument being necessary to be applied in order to cut the previously coagulated tissue. In this regard, sometimes it is difficult to predict which amount of tissue is actually pre-coagulated and can be cut afterwards.
Thus, it would be useful to provide new instruments for parenchymal transections that avoid some of the limitations previously mentioned.